With the rapid growth of the Internet as a public network, users have found its cost effectiveness appealing and continue to deploy media intensive applications and organizational information. The result is a shift from static applications with sparse media content to rich interactive systems with intensive use of media transmitted over various pathways over both public and private networks. The prolific growth of media intensive network applications such as Voice Over IP (VoIP) and video telepresence has driven the interest in understanding why a network can or cannot transmit data over a Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) port and hence the need for network path verification.
Network access providers and operators continue to address concerns of security, network management, and bandwidth control by deploying intervening network devices such as firewalls, content and bandwidth filters, and other data restricting devices between end users of these rich applications. Growth of residential network access devices, such as broadband routers and media gateways, impose transmission restrictions using user configurable and default settings. It is not unusual in today's business environment to have blocked transmissions paths over commonly used protocols and TCP/UDP ports. Utilizing a system for path verification can reveal transmission restrictions in a network and give insight into the mechanism and resolution for such restrictions.
The end user of a path validation system needs to know where data can be successfully transmitted and where it cannot. This knowledge is typically obtained on an almost continuous basis, rather than on a piecemeal approach, as many rich applications utilize several protocols and ports together and hence require verification to run in rapid succession to both emulate actual application data and exercise the decentralized nature of crossing global networks. An automated solution to path validation provides detection of locations along the transmission path where various restrictions may exist.
To be effective, a path validation system must utilize as much network infrastructure as possible along the path under validation. This approach requires transmission of data from inside an operator's own network along a path that may involve multiple public or private networks to a target endpoint and then back along the return path. This represents a complete messaging cycle of send, receive, and reply. Any failures along this path represent different failure modes and yield higher understanding of the network path capabilities.